Webhooks are a simple paradigm for developing instant notifications and mashups based on simple HTTP requests. With HookPress you can set up webhooks so that a specified URL (a public service or something you set up) is requested when certain WordPress actions occur. Possible uses include generating push notifications or using non-PHP web technology to extend WordPress.

To write and host a target script The easiest option is to set up a script on your own server to catch POST requests and act on them. Requestbin is a nice, free service which will host an endpoint, collect all requests, and let you inspect them, which is a great way to test requests generated by your webhooks. There is also a PHP script which does a simple version of this, test.php, included with HookPress.

How does HookPress affect performance?

HookPress currently makes requests synchronously so can measurably affect performance. I highly recommend using a caching plugin such as WP-SuperCache to stem the performance hit. If your filters’ results are time-sensitive or dependent on external data sources as well, make sure to set an appropriate cache expiration time.